Revert "switch GatherPixelRefs to use SkBaseDevice instead of SkBitmapDevice"

This reverts commit 72958c374bdb9457419beeba7de1387da3293882.

BUG=

Review URL: https://codereview.chromium.org/58933007

git-svn-id: http://skia.googlecode.com/svn/trunk/src@12260 2bbb7eff-a529-9590-31e7-b0007b416f81
3 files changed